Recreational use of "ecstasy" (MDMA) is associated with elevated impulsivity

Conflict monitoring and emotional processing in 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine users - A comparative neurophysiological study

In stimulant use and addiction, conflict control processes are crucial for regulating substance use and sustaining abstinence, which can be particularly challenging in social-affective situations. Users of methamphetamine (METH, "Ice") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") both experience impulse control deficits, but display different social-affective and addictive profiles. We thus aimed to compare the effects of chronic use of the substituted amphetamines METH and MDMA on conflict control processes in different social-affective contexts (i.e., anger and happiness) and investigate their underlying neurophysiological mechanisms. For this purpose, chronic but recently abstinent users of METH (n = 38) and MDMA (n = 42), as well as amphetamine-naïve healthy controls (n = 83) performed an emotional face-word Stroop paradigm, while event-related potentials (ERPs) were recorded. Instead of substance-specific differences, both MDMA and METH users showed smaller behavioral effects of cognitive-emotional conflict processing (independently of emotional valence) and selective deficits in emotional processing of anger content. Both effects were underpinned by stronger P3 ERP modulations suggesting that users of substituted amphetamines employ altered stimulus-response mapping and decision-making. Given that these processes are modulated by noradrenaline and that both MDMA and METH use may be associated with noradrenergic dysfunctions, the noradrenaline system may underlie the observed substance-related similarities. Better understanding the functional relevance of this currently still under-researched neurotransmitter and its functional changes in chronic users of substituted amphetamines is thus an important avenue for future research.

Assessing Impulsivity in Humans and Rodents: Taking the Translational Road

Impulsivity is a multidimensional construct encompassing domains of behavioral inhibition as well as of decision making. It is often adaptive and associated with fast responses, being in that sense physiological. However, abnormal manifestations of impulsive behavior can be observed in contexts of drug abuse and attention-deficit/hyperactivity disorder (ADHD), among others. A number of tools have therefore been devised to assess the different facets of impulsivity in both normal and pathological contexts. In this narrative review, we systematize behavioral and self-reported measures of impulsivity and critically discuss their constructs and limitations, establishing a parallel between assessments in humans and rodents. The first rely on paradigms that are typically designed to assess a specific dimension of impulsivity, within either impulsive action (inability to suppress a prepotent action) or impulsive choice, which implies a decision that weighs the costs and benefits of the options. On the other hand, self-reported measures are performed through questionnaires, allowing assessment of impulsivity dimensions that would be difficult to mimic in an experimental setting (e.g., positive/negative urgency and lack of premeditation) and which are therefore difficult (if not impossible) to measure in rodents.

Mephedrone and MDMA: A comparative review

Mephedrone and MDMA are both constituents of party drugs, with mephedrone being relatively new compared to MDMA. This review compares current knowledge regarding the patterns of usage and neuropsychobiological effects of both mephedrone and MDMA. Both drugs share common psychoactive effects, the duration of which is significantly shorter with mephedrone use, attributing towards a pattern of binge use among users. Both drugs have also been associated with adverse health, psychiatric, and neurocognitive problems. Whilst there is extensive research into the psychobiological problems induced by MDMA, the evidence for mephedrone is comparatively limited. The adverse effect profile of mephedrone appears to be less severe than that of MDMA. Users often believe it to be safer, although both drugs have been associated with overdoses. The neurotoxic potential of mephedrone appears to be low, whereas MDMA can cause long-term damage to the serotonergic system, although this needs further investigation. The abuse liability of mephedrone is significantly greater than that of MDMA, raising concerns regarding the impact of lifetime usage on users. Given that mephedrone is relatively new, the effects of long-term exposure are yet to be documented. Future research focused on lifetime users may highlight more severe neuropsychobiological effects from the drug.

An observational study on the sub-acute effects of mephedrone on mood, cognition, sleep and physical problems in regular mephedrone users

RATIONALE

Mephedrone (4-methylmethcathinone; 4-MMC) is a novel recreational drug similar to methylenedioxymethamphetamine (MDMA) and amphetamine. Several adverse effects have been reported, but little is known about its sub-acute effects.

OBJECTIVES

To study sub-acute effects of mephedrone over a period of 9 days.

METHODS

Recreational mephedrone users were recruited and followed over a time period of 9 days. It was recorded whether participants consumed mephedrone or not within the period of testing; those who did were compared to those who did not. Forty-six regular mephedrone users (22 males, 24 females) participated, 21 participants voluntarily opted to consume mephedrone 1-3 days after baseline and 25 opted to abstain. Participants were assessed at baseline on a multitude of measures and provided daily reports on cognition, sleep, mood, physical problems, mephedrone cravings and substance use on each subsequent day of the study. The study controlled for psychopathology, sleep, past and current substance use, impulsivity and demographics.

RESULTS

Those who consumed mephedrone reported persistent negative mood, physical problems and fatigue, compared to those who did not-after controlling for baseline group differences in sleep and subsequent alcohol and cannabis use.

CONCLUSIONS

The results provide the first prospective evidence of the duration and extent of specific undesirable sub-acute effects of mephedrone in regular recreational users and indicate sub-acute effects of mephedrone on mood, fatigue and physical symptoms.

Animal models of drug addiction: Where do we go from here?

Compulsion and impulsivity are both primary features of drug addiction. Based on decades of animal research, we have a detailed understanding of the factors (both environmental and physiological) that influence compulsive drug use, but still know relatively little about the impulsive aspects of drug addiction. This review outlines our current knowledge of the relationship between impulsivity and drug addiction, focusing on cognitive and motor impulsivity, which are particularly relevant to this disorder. Topics to be discussed include the influence of chronic drug administration on impulsivity, the mechanisms that may explain drug-induced impulsivity, and the role of individual differences in the development of impulsive drug use. In addition, the manner in which contemporary theories of drug addiction conceptualize the relationship between impulsivity and compulsion is examined. Most importantly, this review emphasizes a critical role for animal research in understanding the role of impulsivity in the development and maintenance of drug addiction.

Social Cognition and Interaction in Chronic Users of 3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy")

BACKGROUND

The empathogen 3,4-methylenedioxymethamphetamine (MDMA) is the prototypical prosocial club drug inducing emotional openness to others. It has recently been shown that acutely applied 3,4-MDMA in fact enhances emotional empathy and prosocial behavior, while it simultaneously decreases cognitive empathy. However, the long-term effects of 3,4-MDMA use on socio-cognitive functions and social interactions have not been investigated yet. Therefore, we examined emotional and cognitive empathy, social decision-making, and oxytocin plasma levels in chronic 3,4-MDMA users.

METHODS

We tested 38 regular but recently abstinent 3,4-MDMA users and 56 3,4-MDMA-naïve controls with the Movie for the Assessment of Social Cognition, the Multifaceted Empathy Test, and the Distribution Game and the Dictator Game. Drug use was objectively quantified by 6-month hair analyses. Furthermore, oxytocin plasma levels were determined in smaller subgroups (24 3,4-MDMA users, 9 controls).

RESULTS

3,4-MDMA users showed superior cognitive empathy compared with controls in the Multifaceted Empathy Test (Cohen's d=.39) and in the Movie for the Assessment of Social Cognition (d=.50), but they did not differ from controls in emotional empathy. Moreover, 3,4-MDMA users acted less self-serving in the Distribution Game. However, within 3,4-MDMA users, multiple regression analyses showed that higher 3,4-MDMA concentrations in hair were associated with lower cognitive empathy (βMDMA=-.34, t=-2.12, P<.05). Oxytocin plasma concentrations did not significantly differ between both groups.

CONCLUSIONS

We conclude that people with high cognitive empathy abilities and pronounced social motivations might be more prone to 3,4-MDMA consumption. In contrast, long-term 3,4-MDMA use might nevertheless have a detrimental effect on cognitive empathy capacity.

Contribution of Impulsivity and Serotonin Receptor Neuroadaptations to the Development of an MDMA ('Ecstasy') Substance Use Disorder

As is the case with other drugs of abuse, a proportion of ecstasy users develop symptoms consistent with a substance use disorder (SUD). In this paper, we propose that the pharmacology of MDMA, the primary psychoactive component of ecstasy tablets, changes markedly with repeated exposure and that neuroadaptations in dopamine and serotonin brain systems underlie the shift from MDMA use to MDMA misuse in susceptible subjects. Data from both the human and laboratory animal literature are synthesized to support the idea that (1) MDMA becomes a less efficacious serotonin releaser and a more efficacious dopamine releaser with the development of behaviour consistent with an SUD and (2) that upregulated serotonin receptor mechanisms contribute to the development of the MDMA SUD via dysregulated inhibitory control associated with the trait of impulsivity.

Memory Performance in Abstinent 3,4-Methylenedioxymethamphetamine (Mdma, “Ecstasy”) Users

Research with animals and humans has suggested that acute and subacute use of 3,4-methylenedioxymethamphetamine (MDMA “ecstasy”) may lead to memory impairment. However, research is limited by (1) low power due to small sample sizes, (2) the possible confound of polydrug use, and (3) the failure to consider intelligence as a covariate. The present study compared the memory performance on the Wechsler Memory Scale—III of 26 abstinent (2-wk. minimum) recreational MDMA users with 26 abstinent (2-wk. minimum) recreational polydrug users. Despite significantly greater polydrug use amongst these MDMA users, no significant group differences in memory were observed. Regression of total lifetime amount of MDMA use also did not predict memory performance after accounting for intelligence. In addition, the length of time since abstinence (at least 2 wk.) was not associated with an increase in memory performance. Greater total lifetime cocaine use, rather than total lifetime MDMA use, was significantly associated with greater decrements in General Memory and Delayed Verbal Memory performance.

Decision-making in chronic ecstasy users: a systematic review

Different cognitive impairments have been reported as a result of long-term MDMA/ecstasy use. Increased impulsivity and altered decision-making have been shown to be associated with the development and maintenance of addictive disorders pointing toward the necessity to understand a potential impairment of decision-making due to MDMA use. Thus, assessing the long-term effects of MDMA is crucial in order to evaluate its controversially discussed therapeutic use. The aim of this systematic review was to summarize the scientific literature on potential effects of chronic MDMA use on higher order decision-making processes in humans. Therefore, a systematic search for controlled trials relevant to the topic has been performed. Only studies using specific tasks on decision-making were included that involved subjects in the drug-free interval with drug-naïve, and/or polydrug control groups. A total of 12 studies could be identified that met the inclusion criteria, all of which were cross-sectional studies. The findings on decision-making disturbances in MDMA users were heterogeneous. Seven studies reported increased risky decisions, whereas five studies did not find MDMA-specific influences on decision-making. Increased impulsivity was observed both in MDMA groups and in (poly)drug control groups in almost all studies. Thus, the current state of research does not allow for the conclusion that long-term use of MDMA affects decision-making behavior in general. More detailed specifications as well as further investigations of the relevant processes are needed. Significant tendencies toward risky decision-making among long-term MDMA use have been observed, but need to be confirmed by studies using a longitudinal design.

"Ecstasy" toxicity to adolescent rats following an acute low binge dose

BACKGROUND

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy") is a worldwide drug of abuse commonly used by adolescents. Most reports focus on MDMA's neurotoxicity and use high doses in adult animals, meanwhile studies in adolescents are scarce. We aimed to assess in rats the acute MDMA toxicity to the brain and peripheral organs using a binge dose scheme that tries to simulate human adolescent abuse.

METHODS

Adolescent rats (postnatal day 40) received three 5 mg/kg doses of MDMA (estimated equivalent to two/three pills in a 50 kg adolescent), intraperitoneally, every 2 h, while controls received saline. After 24 h animal sacrifice took place and collection of brain areas (cerebellum, hippocampus, frontal cortex and striatum) and peripheral organs (liver, heart and kidneys) occurred.

RESULTS

Significant hyperthermia was observed after the second and third MDMA doses, with mean increases of 1 °C as it occurs in the human scenario. MDMA promoted ATP levels fall in the frontal cortex. No brain oxidative stress-related changes were observed after MDMA. MDMA-treated rat organs revealed significant histological tissue alterations including vascular congestion, but no signs of apoptosis or necrosis were found, which was corroborated by the lack of changes in plasma biomarkers and tissue caspases. In peripheral organs, MDMA did not affect significantly protein carbonylation, glutathione, or ATP levels, but liver presented a higher vulnerability as MDMA promoted an increase in quinoprotein levels.

CONCLUSIONS

Adolescent rats exposed to a moderate MDMA dose, presented hyperthermia and acute tissue damage to peripheral organs without signs of brain oxidative stress.

Meta-analysis of executive functioning in ecstasy/polydrug users

Ecstasy/3,4-methylenedioxymethamphetamine (MDMA) use is proposed to cause damage to serotonergic (5-HT) axons in humans. Therefore, users should show deficits in cognitive processes that rely on serotonin-rich, prefrontal areas of the brain. However, there is inconsistency in findings to support this hypothesis. The aim of the current study was to examine deficits in executive functioning in ecstasy users compared with controls using meta-analysis. We identified k = 39 studies, contributing 89 effect sizes, investigating executive functioning in ecstasy users and polydrug-using controls. We compared function-specific task performance in 1221 current ecstasy users and 1242 drug-using controls, from tasks tapping the executive functions - updating, switching, inhibition and access to long-term memory. The significant main effect demonstrated overall executive dysfunction in ecstasy users [standardized mean difference (SMD) = -0.18, 95% confidence interval (CI) -0.26 to -0.11, Z = 5.05, p < 0.001, I 2 = 82%], with a significant subgroup effect (χ 2 = 22.06, degrees of freedom = 3, p < 0.001, I 2 = 86.4%) demonstrating differential effects across executive functions. Ecstasy users showed significant performance deficits in access (SMD = -0.33, 95% CI -0.46 to -0.19, Z = 4.72, p < 0.001, I 2 = 74%), switching (SMD = -0.19, 95% CI -0.36 to -0.02, Z = 2.16, p < 0.05, I 2 = 85%) and updating (SMD = -0.26, 95% CI -0.37 to -0.15, Z = 4.49, p < 0.001, I 2 = 82%). No differences were observed in inhibitory control. We conclude that this is the most comprehensive analysis of executive function in ecstasy users to date and provides a behavioural correlate of potential serotonergic neurotoxicity.

Crime and Violence among MDMA Users in the United States

The question of whether MDMA use is associated with increased crime and violence has not been adequately explored especially in nationally representative samples. This study used data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to assess the association between MDMA use and violent and non-violent antisocial behavior while controlling for sociodemographic variables, lifetime psychiatric, alcohol and drug use disorders, and family history of antisocial behavior. MDMA users, both male and female, were involved in a number of crimes in acts of violence including drunk driving, shoplifting, theft, intimate partner violence, and fighting. Notably, female MDMA users were more antisocial than male non-MDMA users. Although adjusting the results for numerous confounds attenuated the relationships, MDMA users were still at significantly greater odds of engaging in violent and nonviolent crime than non-MDMA users. Although MDMA has been considered a facilitator of empathy and closeness, the current study suggests a dark side as MDMA is associated with a broad array of crimes and transgressions. Additional tests of the MDMA-crime link are needed to properly inform policy.

Dysfunctional overnight memory consolidation in ecstasy users

Sleep plays an important role in the consolidation and integration of memory in a process called overnight memory consolidation. Previous studies indicate that ecstasy users have marked and persistent neurocognitive and sleep-related impairments. We extend past research by examining overnight memory consolidation among regular ecstasy users (n=12) and drug naïve healthy controls (n=26). Memory recall of word pairs was evaluated before and after a period of sleep, with and without interference prior to testing. In addition, we assessed neurocognitive performances across tasks of learning, memory and executive functioning. Ecstasy users demonstrated impaired overnight memory consolidation, a finding that was more pronounced following associative interference. Additionally, ecstasy users demonstrated impairments on tasks recruiting frontostriatal and hippocampal neural circuitry, in the domains of proactive interference memory, long-term memory, encoding, working memory and complex planning. We suggest that ecstasy-associated dysfunction in fronto-temporal circuitry may underlie overnight consolidation memory impairments in regular ecstasy users.

Ecstasy use and serotonin syndrome: a neglected danger to adolescents and young adults prescribed selective serotonin reuptake inhibitors

BACKGROUND

At present, there are scarce clinical and basic lab data concerning the risk of acute serotonin toxicity from selective serotonin reuptake inhibitors (SSRIs) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) co-administration. The health care community can strongly benefit from efforts to address the high risks associated with serotonin syndrome from this specific drug combination.

OBJECTIVE

The aim of this work is to review the risk of serotonin syndrome in adolescents and young adults prescribed with SSRIs and are concurrently using ecstasy.

DATA SOURCES

An electronic search of the major behavioral science bibliographic databases (Pubmed, PsycINFO, Medline) was conducted to retrieve peer-reviewed articles, which detail the clinical characteristics, biological mechanisms and social implications of SSRIs, MDMA, and their potential synergism in causing serotonin syndrome in the pediatric and young adult population. Search terms included "serotonin syndrome", "ecstasy", "MDMA", "pediatric", and "SSRI". Additional references were incorporated from the bibliographies of these retrieved articles.

RESULTS

MDMA, in combination with the widely-prescribed SSRI antidepressant class, can lead to rapid, synergistic rise of serotonin (5-HT) concentration in the central nervous system, leading to the acute medical emergency known as serotonin syndrome. This review addresses such complication through an exploration of the theoretical mechanisms and clinical manifestations of this life-threatening pharmacological interaction.

CONCLUSION

The increasing incidences of recreational ecstasy use and SSRI pharmacotherapy among multiple psychiatric disorders in the adolescent population have made this an overlooked yet increasingly relevant danger, which poses a threat to public health. This can be curbed through further research, as well as greater health care provision and attention from a regulatory body owing.

Using Cloninger's temperament scales to predict substance-related behaviors in adolescents: a prospective longitudinal study

BACKGROUND AND OBJECTIVES

We tested one of Cloninger's temperament theories - that high novelty seeking (NS), along with low harm avoidance (HA), reward dependence (RD), and persistence (PE), predicts early-onset substance problems.

METHODS

In a community-based sample of 777 adolescents examined at two time points (mean age 13 and 18, respectively), we examined whether Cloninger's four temperament dimensions at wave 1 predicted five substance-related outcomes at wave 2: age of initiation for cigarettes, alcohol, and illicit drugs, number of substance classes tried, and total number of DSM-IV substance use disorder (SUD) symptoms.

RESULTS

Cloninger's predicted temperament pattern did significantly predict the number of SUD symptoms at wave 2. For initiation of cigarettes/illicit drugs and number of substance classes tried, HA/NS/PE fit the pattern, but RD did not. For onset of alcohol, only NS and PE fit Cloninger's prediction. Results for NS and PE were most consistent.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Overall, this study provides evidence that Cloninger's theory may hold true for predicting problem use more than for predicting "use" or experimentation. In addition, youth with high novelty seeking and low persistence may find substances especially reinforcing, and identifying these youth and intervening before initiation has occurred may reduce the risk of future substance-related problems.

Neurotoxicity of methamphetamine and 3,4-methylenedioxymethamphetamine

Amphetamines are a class of psychostimulant drugs that are widely abused for their stimulant, euphoric, empathogenic and hallucinogenic properties. Many of these effects result from acute increases in dopamine and serotonin neurotransmission. Subsequent to these acute effects, methamphetamine and 3,4 methylenedioxymethamphetamine (MDMA) produce persistent damage to dopamine and serotonin nerve terminals. This review summarizes the numerous interdependent mechanisms including excitotoxicity, mitochondrial damage and oxidative stress that have been demonstrated to contribute to this damage. Emerging non-neuronal mechanisms by which the drugs may contribute to monoaminergic terminal damage, as well as the neuropsychiatric consequences of this terminal damage are also presented. Methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) have similar chemical structures and pharmacologic properties compared to other abused substances including cathinone (khat), as well as a relatively new class of novel synthetic amphetamines known as 'bath salts' that have gained popularity among drug abusers.

Deficient fear recognition in regular cocaine users is not attributable to elevated impulsivity or conduct disorder prior to cocaine use

We previously reported that regular recreational intranasal cocaine users exhibit impaired recognition of facial expressions of fear compared to occasional cocaine users and cocaine-naïve controls. The aim of the present study was to re-investigate this phenomenon after controlling for impulsivity, conduct disorder (CD) and anti-social personality disorder (ASPD). We employed a cross-sectional design to compare 31 cocaine-naïve participants, 35 occasional cocaine users and 20 regular recreational cocaine users. An emotional facial expression (EFE) task which comprised a male and a female face expressing six basic emotions morphed to differing degrees of emotional intensity was administered together with questionnaires to assess: CD, ASPD and impulsiveness. ASPD was not a significant covariate for EFE performance but impulsiveness and CD were significant covariates. After treating impulsiveness and CD as covariates we again observed a group difference in fear recognition ability attributable to the particularly impaired performance of regular cocaine users. This suggests that, although elevated impulsiveness and CD before the age of 15 years, may predispose a relative inability to recognize facial expressions of fear in adulthood, subsequent regular recreational use of cocaine represents an additional factor that is specifically associated with a selective deficit in fear recognition.

Neuropsychiatric symptom assessments in toxic exposure

The goal of this review is to provide guidelines for evaluating psychiatric and mood changes that result from neurotoxicity. Mood changes that are often seen to varying degrees in neurotoxicity include increased anxiety, depression, irritability, impulsiveness, and psychosis. Some common agents that induce neurotoxicity include drugs, heavy metals, and organophosphates with presentations varying somewhat depending upon the mechanism of toxicity. The authors discuss in detail psychiatric assessment for patients with suspected of having neurotoxicologic syndrome.

Effects of acute MDMA intoxication on mood and impulsivity: role of the 5-HT2 and 5-HT1 receptors

MDMA induces positive mood and increases impulse control during intoxication, but only a few studies on the neuropharmacological mechanisms underlying these processes have been conducted. It was hypothesized that pretreatment with 5-HT₁ and 5-HT₂ receptor blockers would prevent MDMA effects on mood and impulsivity. Subjects (N = 17) participated in a double-blind, placebo controlled, within-subject design involving 6 experimental conditions consisting of pretreatment (T1) and treatment (T2). T1 preceded T2 by 30 minutes. T1–T2 combinations were: placebo-placebo, 20 mg pindolol-placebo, 50 mg ketanserin-placebo, placebo-75 mg MDMA, 20 mg pindolol-75 mg MDMA and 50 mg ketanserin-75 g MDMA. Subjects completed a Profile of Mood States (POMS) questionnaire and several impulsivity tasks (Stop signal task, Matching familiar figures task, Cue dependent reversal learning task) at 1.5 hrs post-treatment. MDMA alone increased both positive (vigor, arousal, friendliness, elation, positive mood) and negative affect (anxiety, confusion) as assessed by the POMS questionnaire. MDMA also increased stop reaction time in the Stop signal task and reaction time in the Matching familiar figures task. Pretreatment with ketanserin blocked MDMA effects on positive affect, but not negative affect. Ketanserin did not influence the effects of MDMA on impulsivity. Pindolol did not interact with MDMA on any of the measures. In conclusion, 5-HT₂ receptors mediate positive moods induced by MDMA but not negative moods or impulsivity. 5-HT₁ receptors do not appear to be involved in MDMA effects on mood and impulse control.

Substrates of neuropsychological functioning in stimulant dependence: a review of functional neuroimaging research

Stimulant dependence is associated with neuropsychological impairments. Here, we summarize and integrate the existing neuroimaging literature on the neural substrates of neuropsychological (dys)function in stimulant dependence, including cocaine, (meth-)amphetamine, ecstasy and nicotine dependence, and excessive caffeine use, comparing stimulant abusers (SAs) to nondrug using healthy controls (HCs). Despite some inconsistencies, most studies indicated altered brain activation in prefrontal cortex (PFC) and insula in response to reward and punishment, and higher limbic and anterior cingulate cortex (ACC)/PFC activation during craving and attentional bias paradigms in SAs compared with HCs. Impulsivity in SAs was associated with lower ACC and presupplementary motor area activity compared with HCs, and related to both ventral (amygdala, ventrolateral PFC, insula) and dorsal (dorsolateral PFC, dorsal ACC, posterior parietal cortex) systems. Decision making in SAs was associated with low dorsolateral PFC activity and high orbitofrontal activity. Finally, executive function in SAs was associated with lower activation in frontotemporal regions and higher activation in premotor cortex compared with HCs. It is concluded that the lower activations compared with HCs are likely to reflect the neural substrate of impaired neurocognitive functions, whereas higher activations in SAs compared with HCs are likely to reflect compensatory cognitive control mechanisms to keep behavioral task performance to a similar level as in HCs. However, before final conclusions can be drawn, additional research is needed using neuroimaging in SAs and HCs using larger and more homogeneous samples as well as more comparable task paradigms, study designs, and statistical analyses.

Are executive function and impulsivity antipodes? A conceptual reconstruction with special reference to addiction

RATIONALE

Although there is considerable interest in how either executive function (EF) or impulsivity relate to addiction, there is little apparent overlap between these research areas.

OBJECTIVES

The present paper aims to determine if components of these two constructs are conceptual antipodes--widely separated on a shared continuum.

METHODS

EFs and impulsivities were compared and contrasted. Specifically, the definitions of the components of EF and impulsivity, the methods used to measure the various components, the populations of drug users that show deficits in these components, and the neural substrates of these components were compared and contrasted.

RESULTS

Each component of impulsivity had an antipode in EF. EF, however, covered a wider range of phenomena, including compulsivity.

CONCLUSIONS

Impulsivity functions as an antipode of certain components of EF. Recognition of the relationship between EF and impulsivity may inform the scientific inquiry of behavioral problems such as addiction. Other theoretical implications are discussed.

Dopamine, serotonin and impulsivity

Impulsive people have a strong urge to act without thinking. It is sometimes regarded as a positive trait but rash impulsiveness is also widely present in clinical disorders such as attention deficit hyperactivity disorder (ADHD), drug dependence, mania, and antisocial behaviour. Contemporary research has begun to make major inroads into unravelling the brain mechanisms underlying impulsive behaviour with a prominent focus on the limbic cortico-striatal systems. With this progress has come the understanding that impulsivity is a multi-faceted behavioural trait involving neurally and psychologically diverse elements. We discuss the significance of this heterogeneity for clinical disorders expressing impulsive behaviour and the pivotal contribution made by the brain dopamine and serotonin systems in the aetiology and treatment of behavioural syndromes expressing impulsive symptoms.

The effects of 'ecstasy' (MDMA) on visuospatial memory performance: findings from a systematic review with meta-analyses

To review, with meta-analyses where appropriate, performance differences between ecstasy (3,4-methylenedioxymethamphetamine) users and non-users on a wider range of visuospatial tasks than previously reviewed. Such tasks have been shown to draw upon working memory executive resources. Abstract databases were searched using the United Kingdom National Health Service Evidence Health Information Resource. Inclusion criteria were publication in English language peer-reviewed journals and the reporting of new findings regarding human ecstasy-users' performance on visuospatial tasks. Data extracted included specific task requirements to provide a basis for meta-analyses for categories of tasks with similar requirements. Fifty-two studies were identified for review, although not all were suitable for meta-analysis. Significant weighted mean effect sizes indicating poorer performance by ecstasy users compared with matched controls were found for tasks requiring recall of spatial stimulus elements, recognition of figures and production/reproduction of figures. There was no evidence of a linear relationship between estimated ecstasy consumption and effect sizes. Given the networked nature of processing for spatial and non-spatial visual information, future scanning and imaging studies should focus on brain activation differences between ecstasy users and non-users in the context of specific tasks to facilitate identification of loci of potentially compromised activity in users.

Assessing topographical orientation skills in cannabis users

The long-term effects of cannabis on human cognition are still unclear, but, considering that cannabis is a widely used substance and, overall, its potential use in therapeutic interventions, it is important to evaluate them. We hypothesize that the discrepancies among studies could be attributed to the specific cognitive function investigated and that skills subserved by the hippocampus, such as the spatial orientation abilities and, specifically, the ability to form and use cognitive maps, should be more compromised than others. Indeed it has been showed that cannabis users have a reduced hippocampus and that the hippocampus is the brain region in which cannabis has the greatest effect since it contains the highest concentration of cannabinoid receptors. To test this hypothesis we asked 15 heavy cannabis users and 19 nonusers to perform a virtual navigational test, the CMT, that assesses the ability to form and use cognitive maps. We found that using cannabis has no effect on these hippocampus-dependent orientation skills. We discuss the implications of our findings and how they relate to evidence reported in the literature that the intervention of functional reorganization mechanisms in cannabis user allows them to cope with the cognitive demands of navigational tasks.

Evidence for chronically altered serotonin function in the cerebral cortex of female 3,4-methylenedioxymethamphetamine polydrug users

CONTEXT

MDMA (3,4-methylenedioxymethamphetamine, also popularly known as "ecstasy") is a popular recreational drug that produces loss of serotonin axons in animal models. Whether MDMA produces chronic reductions in serotonin signaling in humans remains controversial.

OBJECTIVE

To determine whether MDMA use is associated with chronic reductions in serotonin signaling in the cerebral cortex of women as reflected by increased serotonin(2A) receptor levels.

DESIGN

Cross-sectional case-control study comparing serotonin(2A) receptor levels in abstinent female MDMA polydrug users with those in women who did not use MDMA (within-group design assessing the association of lifetime MDMA use and serotonin(2A) receptors). Case participants were abstinent from MDMA use for at least 90 days as verified by analysis of hair samples. The serotonin(2A) receptor levels in the cerebral cortex were determined using serotonin(2A)-specific positron emission tomography with radioligand fluorine 18-labeled setoperone as the tracer.

SETTING

Academic medical center research laboratory.

PARTICIPANTS

A total of 14 female MDMA users and 10 women who did not use MDMA (controls). The main exclusion criteria were nondrug-related DSM-IV Axis I psychiatric disorders and general medical illness.

MAIN OUTCOME MEASURES

Cortical serotonin(2A) receptor nondisplaceable binding potential (serotonin(2A)BP(ND)).

RESULTS

MDMA users had increased serotonin(2A)BP(ND) in occipital-parietal (19.7%), temporal (20.5%), occipitotemporal-parietal (18.3%), frontal (16.6%), and frontoparietal (18.5%) regions (corrected P < .05). Lifetime MDMA use was positively associated with serotonin(2A)BP(ND) in frontoparietal (β = 0.665; P = .007), occipitotemporal (β = 0.798; P = .002), frontolimbic (β = 0.634; P = .02), and frontal (β = 0.691; P = .008) regions. In contrast, there were no regions in which MDMA use was inversely associated with receptor levels. There were no statistically significant effects of the duration of MDMA abstinence on serotonin(2A)BP(ND).

CONCLUSIONS

The recreational use of MDMA is associated with long-lasting increases in serotonin(2A) receptor density. Serotonin(2A) receptor levels correlate positively with lifetime MDMA use and do not decrease with abstinence. These results suggest that MDMA use produces chronic serotonin neurotoxicity in humans. Given the broad role of serotonin in human brain function, the possibility for therapeutic MDMA use, and the widespread recreational popularity of this drug, these results have critical public health implications.

Reward sensitivity and outcome expectancies as predictors of ecstasy use in young adults

Extending recent studies showing that sensitivity to reward and outcome expectancies are associated with problematic alcohol and cannabis use, we undertook to determine if similar relationships would hold for ecstasy. One hundred and twenty five males and females aged between 18 and 35years were recruited from RMIT University and through snowball sampling. Participants completed a questionnaire package measuring frequency, amount and first age of ecstasy use, sensitivity to reward and punishment as well as outcome expectancies relating to ecstasy use. Frequency of ecstasy use was significantly related to reward sensitivity (p<.05) and positive outcome expectancies (p<.01). Regression analysis revealed significant prediction of ecstasy use by study variables, with expectations of increased confidence making the largest individual contribution. Multiple intervention points are suggested by the results of this study, within a largely cognitive-based framework.

Modelling the adverse effects associated with ecstasy use

AIMS

Ecstasy, the street name for 3,4-meththylenedioxymethamphetamine, has been associated with a range of psychiatric symptoms and impaired psychological health in both problem and recreational users. The purpose of the present paper is to determine how these impairments are related to the history of polydrug use, and the conditions under which individuals ingest ecstasy.

DESIGN

Associations between the variables of interest were investigated utilizing negative binomial regression.

SETTING

Liverpool and Preston in the North West of England.

PARTICIPANTS

A convenience sample of 159 recreational ecstasy/polydrug users (80 males, 79 females). The sample was composed primarily of undergraduates.

MEASUREMENTS

The dependent variable was the number of reported ecstasy-related adverse effects. Independent variables included quantitative aspects of ecstasy and other drug use, and the various beliefs and behaviours associated with ecstasy use.

FINDINGS

The number of adverse effects was associated positively with life-time exposure to ecstasy and negatively with period of abstinence from the drug. Adverse effects were more common among those who consumed ecstasy and alcohol concurrently, but were unrelated to other aspects of polydrug use. They were unaffected by whether the user took precautions when using the drug, and only weakly related to prior beliefs concerning the effects of ecstasy.

CONCLUSIONS

Greater life-time exposure to ecstasy and consuming the drug concurrently with alcohol increase the likelihood of experiencing adverse effects, including paranoia, poor general health, irritability, confusion and moodiness. Adverse effects decrease with the period of abstinence from the drug.

Neural correlates of choice behavior related to impulsivity and venturesomeness

Impulsivity has been associated with several psychiatric disorders including drug addiction and gambling. Impulsive subjects typically have a preference for short-term over long-term rewards and make risky choices. This study used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of self-rated impulsivity and venturesomeness during tasks involving delayed and risky choice. A broader sampling approach was taken by recruiting participants with behaviors that have been linked to impulsivity (gambling N=15, and recreational drug use N=10) and those without these behaviors (N=9). Selection between delayed or probabilistic rewards was associated with activation in fronto-parietal regions in line with previous research. When selecting between delayed rewards, activity within the pregenual anterior cingulate cortex and ventrolateral prefrontal cortex correlated positively with impulsivity scores while activity within the orbitofrontal cortex, subgenual anterior cingulate cortex and caudate correlated positively with venturesomeness scores. Selection between probabilistic rewards revealed no correlation between scores and regional activations. The results from this study provide targets for future research investigating the neural substrates of impulsivity. They also provide targets for the further investigation into the pathophysiology of addiction and impulse-control disorders.

Reflection-Impulsivity Assessed Through Performance Differences in a Computerized Spatial Task

This study focuses on performance differences individuals show when solving a computerized spatial-orientation dynamic task, irrespective of their cognitive ability. The hypothesis tested was that differences in performance reflect individuals’ cognitive style: Reflection-Impulsivity. The Spatial Orientation Dynamic Task-Revised (SODT-R) and the Analytical, Sequential, and Inductive Reasoning Test (TRASI) were administered to 541 postgraduate participants, as part of the selection process they were following. Reflection-Impulsivity was measured through average response latency and average error score comprising three groups: impulsive, reflective, and medium. Performance was measured by mean response frequency, quality proportion of the first press, and mean invested time. Data were analyzed through discriminant analysis. Criterion variable was Reflection-Impulsivity groups and discriminant variables were performance ones, plus intelligence. Results show different performance patterns clearly associated with Reflection-Impulsivity (canonical correlation = .63). Intelligence played a small role in the differentiation between groups. Findings support the proposal to use spatial orientation tasks as vehicles to measure cognitive style Reflection-Impulsivity in adults. We finally discuss performance patterns as a pathway to ways of acquiring and processing spatial information for impulsives and reflexives, with similar cognitive resources.

The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

Deficits in verbal fluency associated with ecstasy use have been well established; however, the mechanisms underlying this impairment have yet to be elucidated. In this study we investigated for the first time whether there was a disproportionate impairment in two cognitive subcomponents of verbal fluency: clustering (ability to generate words within the same subcategory) and switching (ability to change the subcategory). We also investigated a possible association between ecstasy use and verbal fluency in subjects genotyped for 5-HTT (5-HTTLPR and 5-HTTVNTR) and COMT (val(108/158)met, rs165599 and rs2097603) polymorphisms, in order to find a potential implication of genetic factors. Ecstasy polydrug users (n = 30) and non-ecstasy users (n = 41) were evaluated in both semantic and phonemic fluency. Results showed that ecstasy users had poorer semantic (but not phonemic) fluency performance than controls. Detailed analysis of clustering and switching performance revealed that this impairment was associated with poorer clustering mechanisms. Clustering was also modulated by the COMT rs165599 polymorphism independently of the group. A specific effect of the 5-HTTLPR polymorphism on switching performance was also found, with ss carriers performing significantly worse than ls and ll carriers, suggesting a serotonin modulation of frontal-executive flexibility. Based on the impaired clustering and switching strategies observed in ecstasy users, it might be proposed that both semantic knowledge and retrieval are impaired in this population. The verbal fluency deficit in ecstasy users may be attributable to a disruption of frontal-striatal circuits directly related with the serotonin function as well as a depletion of lexical-semantic stores mediated by temporal structures.

Substance use in adolescence and psychosis: clarifying the relationship

Adolescence is a time of exploration of the self, and this exploration may involve the use of alcohol and drugs. Sadly, for some, adolescence also marks the first signs of a psychosis. The temporal proximity between the onset of substance use and of psychosis has been the cause of much debate. Here we review the association of alcohol, cannabis, stimulants, and other drugs with psychosis, and we conclude that the use of cannabis and the amphetamines significantly contributes to the risk of psychosis.

Neurocognitive impairments in MDMA and other drug users: MDMA alone may not be a cognitive risk factor

BACKGROUND

MDMA (3,4-methylenedioxymethamphetamine; "Ecstasy") is an amphetamine derivative with mild hallucinogenic and stimulant qualities. MDMA leads to serotonin (5-hydroxytryptamine; 5-HT) neurotoxicity and has been linked to cognitive impairments. It remains unclear whether these impairments are due to MDMA versus other drug use.

METHOD

Neurocognitive functioning was measured in a sample of abstinent polydrug users (n = 52) with a range of MDMA use and healthy nondrug controls (n = 29). Participants completed a comprehensive neuropsychological battery and self-report measures of drug use.

RESULTS

Polydrug users performed worse than controls on spatial span and spatial working memory (ps < .05). Among polydrug users, lifetime marijuana use significantly predicted verbal learning and memory performance (p < .01), while MDMA use was not predictive of cognitive impairment.

CONCLUSIONS

This study and our previous report (Hanson, Luciana, & Sullwold, 2008) suggest that moderate MDMA use does not lead to persistent impairments above and beyond that associated with generally heavy drug use, but polydrug use may lead to dose-related temporal and frontoparietal dysfunction. Marijuana use may be particularly problematic. Cause-effect relations are unclear.

Significant association between the C(-1019)G functional polymorphism of the HTR1A gene and impulsivity

Serotonin-1A (5-HT(1A)) receptors are known to play a role in impulsivity-related behavior. The C(-1019)G functional polymorphism (rs6295) has been suggested to regulate the 5-HT(1A) receptor gene (HTR(1A)) expression in presynaptic raphe neurons, namely, increased receptor concentration and reduced neuronal firing could be associated with the G allele. Previous studies indicate that this polymorphism is associated with aggression, suicide, and several psychiatric disorders, yet its association with impulsivity has rarely been investigated. We studied the relationship between impulsivity and the C(-1019)G polymorphism of the HTR(1A) in a population sample of 725 volunteers using the Impulsiveness subscale (IVE-I) of the Eysenck Impulsiveness, Venturesomeness, and Empathy scale and also the Barratt Impulsiveness Scale (BIS-11). Data were analyzed using analysis of variance with age and gender as covariates and Tukey's HSD post-hoc test. Post-hoc analysis revealed that the study had 0.958 power to detect 0.15 effect size. Significant differences between the C(-1019)G genotype groups (GG vs. GC vs. CC) were found. Subjects carrying GG genotype showed significantly higher impulsiveness scores compared to GC or CC carriers for the IVE-I scale (P = 0.014), for the Motor (P = 0.021), Cognitive Impulsiveness (P = 0.002), and for the BIS total score (P = 0.008) but not for the Nonplanning Impulsiveness (P = 0.520) subscale of the BIS-11. Our results suggest the involvement of the HTR(1A) in the continuum phenotype of impulsivity.

Cognitive impulsivity in Parkinson's disease patients: assessment and pathophysiology

Impulsivity may be induced by therapeutic interventions (dopamine replacement therapies and sub-thalamic nucleus (STN) stimulation) in patients with Parkinson's disease (PD). The present review has two goals. First, to describe the most frequently encountered facets of cognitive impulsivity and to stress the links between cognitive impulsivity and aspects such as reward-related decision making, risk-taking, and time-processing in healthy population. The most widely used related cognitive impulsivity paradigms are presented. Second, to review the results of studies on cognitive impulsivity in healthy volunteers and in patients with PD, the latter support the applicability and clinical relevance of this construct in PD population. Data show that PD treatments may favor impulsivity via different mechanisms. Suggestions on the roles of dopamine and STN in the pathophysiology of cognitive impulsivity are proposed.

Deficits of long-term memory in ecstasy users are related to cognitive complexity of the task

RATIONALE

Despite animal evidence that methylenedioxymethamphetamine (ecstasy) causes lasting damage in brain regions related to long-term memory, results regarding human memory performance have been variable. This variability may reflect the cognitive complexity of the memory tasks. However, previous studies have tested only a limited range of cognitive complexity. Furthermore, comparisons across different studies are made difficult by regional variations in ecstasy composition and patterns of use.

OBJECTIVES

The objective of this study is to evaluate ecstasy-related deficits in human verbal memory over a wide range of cognitive complexity using subjects drawn from a single geographical population.

MATERIALS AND METHODS

Ecstasy users were compared to non-drug using controls on verbal tasks with low cognitive complexity (stem completion), moderate cognitive complexity (stem-cued recall and word list learning) and high cognitive complexity (California Verbal Learning Test, Verbal Paired Associates and a novel Verbal Triplet Associates test). Where significant differences were found, both groups were also compared to cannabis users.

RESULTS

More cognitively complex memory tasks were associated with clearer ecstasy-related deficits than low complexity tasks. In the most cognitively demanding task, ecstasy-related deficits remained even after multiple learning opportunities, whereas the performance of cannabis users approached that of non-drug using controls. Ecstasy users also had weaker deliberate strategy use than both non-drug and cannabis controls.

CONCLUSIONS

Results were consistent with the proposal that ecstasy-related memory deficits are more reliable on tasks with greater cognitive complexity. This could arise either because such tasks require a greater contribution from the frontal lobe or because they require greater interaction between multiple brain regions.

Big losses lead to irrational decision-making in gambling situations: relationship between deliberation and impulsivity

In gambling situations, we found a paradoxical reinforcing effect of high-risk decision-making after repeated big monetary losses. The computerized version of the Iowa Gambling Task (Bechara et al., 2000), which contained six big loss cards in deck B', was conducted on normal healthy college students. The results indicated that the total number of selections from deck A' and deck B' decreased across trials. However, there was no decrease in selections from deck B'. Detailed analysis of the card selections revealed that some people persisted in selecting from the "risky" deck B' as the number of big losses increased. This tendency was prominent in self-rated deliberative people. However, they were implicitly impulsive, as revealed by the matching familiar figure test. These results suggest that the gap between explicit deliberation and implicit impulsivity drew them into pathological gambling.

An investigation of the subacute effects of ecstasy on neuropsychological performance, sleep and mood in regular ecstasy users

The aim of this study was to differentiate the subacute from the chronic effects of ecstasy. Regular ecstasy users who subsequently chose to take ecstasy (experimental group: E, N = 16) were compared with regular ecstasy users who opted not to (control group: C, N = 16). Groups were assessed with neuropsychological and psychometric measures at drug-free baseline before ecstasy use and 1 and 4 days after use. Ecstasy users who consumed ecstasy (E) did not differ from those who did not (C) in relation to age, estimated IQ, personality or past substance use, including ecstasy. At baseline, E reported being more energetic, lively and cheerful whereas the day after ecstasy use they reported being more muddled, afraid, sad and dejected than C. However, this was not significant after controlling for sleep deprivation. Mood returned to baseline within 3 days and there were no group differences in Beck depression inventory scores at any of the three testing sessions. There were no subacute effects of ecstasy on working memory, story recall, impulsivity, or decision-making. However, at baseline and the day after use ecstasy users made poorer decisions, and were less sensitive to punishment, in the Somatic marker sensitivity test. These findings suggest that previous reports of marked subacute effects of ecstasy use may have been confounded by chronic polydrug use before use, co-substance use and sleep disturbances after use.